To meet the requirements of electromagnetic launch devices, this article proposes a cascaded high-voltage power supply topology based on integrated charging and discharging of lithium batteries for pulsed capacitor charging. Lithium batteries are used as long-term energy storage units to meet the mobility requirements of electromagnetic launch devices, and only one charger module is used to fully charge all battery power to realize the lightweight of electromagnetic launch devices. A multistage constant current charging (CC Charge) strategy is proposed based on this topology, which can fully charge all batteries at the same time. In addition, for the discharge of the battery to the pulsed capacitor, a double closed-loop PI control strategy with outer-loop output limiting is proposed to realize stable and CC Charge of the pulsed capacitor to 7000 V, which improves the operational stability of electromagnetic launch devices. A MATLAB/Simulink simulation model is built to verify the charging and discharging control strategy, and the results show the effectiveness of the proposed circuit topology and control strategy, which can reduce the complexity of electromagnetic launch devices and control the batteries to discharge stably at constant current.

This paper focuses on the trigger angle adjustment of thyristor rectifiers adapted to pulsed alternators. Firstly, the working principles of the pulsed alternator power system driving electromagnetic rail load with diode-type power converter and thyristor-type power converter are compared. Then, the matching problem between the multiphase pulsed alternator and the thyristor pulse power converter is discussed, and the influence of the load and the mutual inductance of the machine on the adjustment range of the thyristor triggering angle is deeply analyzed. On this basis, a trigger angle adjustment method is proposed to apply to the interference of a strong magnetic field environment, and the constraints to be satisfied to ensure its normal operation are analyzed. Finally, an experimental platform for pulsed power supply based on a multiphase air-core pulsed alternator is constructed, and relevant experimental research is carried out to provide reference for the further engineering application of the pulsed alternator.

The application of a multiphase air-core pulsed alternator (APA) power supply system in railgun has been studied. First, the working principle of the multiphase APA power supply system driving the railgun is introduced in detail, and the mathematical models of the multiphase APA and the railgun are given. Second, the discharge characteristics of the multiphase APA power supply system are analyzed. The relationship between the load current and the phase current is expounded at the theoretical level, and the characteristics such as the amplitude and pulsewidth of the phase current during the discharge process of the eight-phase motor are analyzed and parsed. Then, a field-circuit coupling simulation model is constructed to simulate and analyze the discharge process of the multiphase APA driving the railgun, verifying the correctness of the theoretical analysis. Finally, the experimental platform of multiphase APA driving the railgun is built, and the launch experiments are successfully conducted. Meanwhile, valuable experimental data are also provided for the subsequent further experiments.

To meet the requirements of the electromagnetic rail launch system for a large-scale pulsed power supply to output stable discharge current, seeking a fast solution method for the discharge sequence and obtaining a reasonable triggering sequence is a key direction of research on large-scale pulsed power supply. This article proposes a sequence solution strategy based on charge equivalent. Based on the principle of equal charge amounts during the discharge process, the relationship between the current waveforms and the number of modules at different stages is obtained. Then, the triggering sequence of each module is solved according to the set current requirements. A typical representative system was established to verify the feasibility and accuracy of the above solution strategy. The results show that the triggering sequence obtained by the solution strategy can make the discharge current meet the requirements and improve the solution efficiency. The sequence solution strategy based on charge equivalent can not only avoid complex mathematical calculations to obtain the triggering sequence, but also effectively improve the discharge success rate of the engineering test.

Pulsed alternators exhibit multifunctional capabilities, including inertial energy storage, energy conversion, and pulse shaping, rendering them a crucial class of pulse power sources. The development of air-core and multiphase structures represents a prominent trend in pulsed alternator technology. This paper focuses on the investigation of an eight-phase air-core pulsed alternator, analyzing its electromagnetic characteristics and its ultimate current output capability. First, an analytical calculation model is established to determine the electromagnetic parameters. Subsequently, an in-depth discussion elucidates the analytical relationship between the pulsed alternator's ultimate output capability and its intrinsic parameters, clarifying the factors influencing the output current capability. Second, a three-dimensional field-circuit coupled finite element analysis model is constructed to analyze the magnetic field distribution characteristics and output characteristics of the pulsed alternator. Finally, a multiphase pulsed alternator experimental platform is constructed, and preliminary experimental research is conducted, laying a theoretical and experimental foundation for the optimization design and engineering application of pulsed alternators.

With the scale of pulse forming network expanding and the number of power modules increasing, a time sequence signal generator is limited by the number of channels, which shows the disadvantages in different application scenarios. To solve the problem of limited channel number of a signal generator, an expansion scheme is designed by adding another device to the existing generator, which realizes the cascade expansion of two signal generators and increases the maximum number of available channels. Aiming at the consistency of the integrated control and parameter setting of the two signal generators, the host computer software is developed with Qt Creator, two serial communication channels are set up to connect with the two sub-computer devices, and the output signals of the two devices are managed and controlled comprehensively. Aiming at the localization replacement of core components of time sequence signal generator, one of the devices uses domestic FPGA as the main control chip to complete the time sequence logic control design. Under the unified control of the host computer, the two time sequence signal generators can output the time sequence pulse signals according to the set parameters. When receiving software trigger signals from the host computer, the synchronization error between two devices is approximately 840 microseconds. However, establishing a hardware connection between the two devices significantly reduces this synchronization error to 20 ns when transmitting external trigger inputs from one device to another. This enhancement effectively facilitates cascading expansion of the two devices. For the discharge control of pulse forming network, the channel combinations of time sequence signal generator can be flexibly selected according to the number of power modules to ensure the normal operation of the system.

The cascaded circuit topology of charging power supply for pulse capacitor is a new type of charging circuit topology for pulse capacitor, which is especially suitable for megawatt output power of single machine. Based on the topology of cascaded pulse capacitor charging power supply and multi-carrier modulation technology, this paper proposes the carrier phase shifting sum carrier disposition composite control strategy. On the basis of realizing the automatic current closed-loop and improving the load adaptability of the power supply, it further solves the problems of large charging current ripple and large switching loss. Finally, a simulation model of the charging power supply is built in Simulink environment. The simulation results verify the feasibility of the control strategy. When the inductance, switching frequency, input voltage and other conditions are determined, the ripple coefficient is only 4.23%, which effectively reduces the current stress of the power switch device.

In this paper, a new type of low-voltage electromagnetic riveting device used in aeronautical manufacturing field is developed. The electromagnetic riveting device is designed with the principle of reluctance. The electromagnetic riveting device comprises two helical coils, which respectively is the main coil and the reset coil. When the main coil is working, the iron material armature is driven to move forward to impact the rivet, with the impact pressure of 80 kN. In the working voltage of 400 V and energy storage of 1600 J state, it can easily complete the riveting process of the diameter of 5mm aluminum rivet. The resetting coil can pull the iron armature back to the initial position and hold on. The new type electromagnetic riveting device can be automatically controlled. The riveting, returning and holding function can be finished in the sequence, with the frequency 15 times a minute.

The development of electromagnetic launch technology imposes higher requirements on the discharge control of Pulse Forming Networks (PFN). This paper introduces a multi-channel time sequence pulse signal generating platform based on FPGA NiosII system. The user logic is designed by employing modular programming methodologies. Furthermore, the host computer software is developed utilizing the Qt Creator to facilitate comprehensive control over 30-channel output pulse signals. Within a short delay range, the adjustment step size of channel output time sequence can reach 20ns. To meet various discharge requirements, the signal generator is designed with the capability to store multiple sets of time sequence data. Upon receiving of a designated group number, it promptly calls the corresponding time sequence to generate trigger pulses, thereby swiftly modulating the output current waveform of the PFN. To verify the correctness of the FPGA logic program, SignalTap II Logic Analyzer, an embedded logic analyzer of the Quartus platform, is used to logically judge the FPGA output signals. Additionally, a digital oscilloscope is employed for precise measurement of analog signals from FPGA pins. The experimental waveforms demonstrate that the FPGA logic program meets the design requirements. The connection between host computer and FPGA is established through serial communication for joint debugging and testing. In order to test the signal generator's adjustment functionality of time sequence, the host computer issues the group number. Test results substantiate that output pulse signals of the signal generator are accordant with the setting of the host computer, and the generator can update the output time sequence online based on the received group number. Applying this signal generator to PFN systems allows flexible adjustment of multi-module trigger time sequence according to discharge waveform requirements, which is beneficial for improving the discharge accuracy of PFN systems and expanding their application environment.

A pulsed alternator (PA) is an important pulse power source capable of driving many types of loads. For electromagnetic rail launcher load, the ideal driving current is a flat top wave. However, the discharge current of the PA will decline, resulting in the inability to maintain a flat top during pulse discharge. Therefore, an optimization method of discharge current based on excitation compensation is proposed and compared it with the traditional method of adjusting the trigger angle (ATA) in this article. First, the relationship between field current and discharge current is analyzed theoretically, and the optimization method is verified. Second, three optimization methods: ATA, separate-excitation compensation (SEC1), and self-excitation compensation (SEC2) were compared. Then, a comparative analysis was conducted on the optimization strategies for the combination of multimethods. Finally, the PA inductance parameters were extracted by using the finite element method (FEM), and the FEM and circuit coupling simulation and the circuit simulation were compared to verify the accuracy of the circuit model and the superiority of the optimization strategies. The results show that all three optimization methods have obvious merits and demerits. The optimization strategies can balance the merits and demerits of a single method and obtain great benefits at small costs. Especially the ATA $+$ SEC2 and ATA $+$ SEC1 $+$ SEC2 optimization strategies are the most prominent. The former does not require external energy compared to the latter, at the cost of a slightly higher field current peak; the latter can achieve the recovery of residual energy in the rails for excitation compensation in the next pulse discharge, at the cost of requiring a set of devices for the residual energy recovery in the rails.

Capacitive pulsed power supply (CPPS) has been obtained widespread applications because of its plenty of superiorities. The circuit model is developed, and the synchronous discharge process is investigated at first. Then, the synchronous discharge analytical model is developed for the system. The correctness of the analytical model is validated by simulation. To solve the power parameters quickly, the PC software is developed based on this analytical model to meet the experimental requirements. Finally, taking an experimental system as an example, the accuracy of the proposed model is demonstrated by comparing the simulation and experimental results. By developing the synchronous discharge analytical model, it provides an essential reference for CPPS control strategy for further investigation.

Pulsed alternator is widely concerned in the field of pulse power supply, and the heat generation of the field coil is an important reason for the temperature rise of the rotor, which is unfavorable to the thermal management of the pulsed alternator. Therefore, a parallel excitation and serial recovery magnetic energy recovery topology for the separate excitation pulsed alternator is proposed in this article. In contrast with the conventional (no recovery) topology, there are two changes in this topology. One is that the diode is replaced by a thyristor in freewheeling circuit, which can realize the switching of the field current from the freewheeling state to the recovery state. The other is that serial recovery topology is used, which can realize the rapid recovery of magnetic energy. First, the analytical expressions of the field current and the pulse capacitor voltage are derived under the three states of parallel excitation, freewheeling, and serial recovery. Second, four performance parameters for evaluating topology are derived based on the obtained analytical expressions. Third, the influence of the number of serial modules $n$ on the four performance parameters is analyzed. Finally, the maximum value of $n$ is solved, and the simulation models under different $n$ values are built. The simulation results verify the correctness of the analytical model and the benefits and losses of the magnetic energy recovery topology are discussed.

Cascade charging topology of battery pack is a new topology for high-power charging of high-voltage pulse capacitors, and loop resistance is one of the key parameters of this circuit. Based on the equivalent circuit of cascade charging topology, the influence of loop resistance parameters on charging current waveform (battery pack access time, ripple coefficient, charging time) and charging efficiency is deeply analyzed. Based on the analysis conclusion, considering charging time and charging efficiency, the optimal loop resistance parameters are obtained by MATLAB simulation for a 16 MJ/1.4 kV capacitive energy storage system, and the average charging speed of the charging power supply reaches 2.3 MJ/s under the constraint of the maximum current of 1400 A.

The high-rate discharging performance of lithium titanate batteries is a crucial aspect of their functionality. Under high-power demands, the discharge rate, which is defined as the ratio of discharge current to the maximum capacity, can exceed 50 C or higher. This study investigates the evolution of incremental capacity (IC) curves and frequency response characteristic of 2 Ah lithium titanate batteries subjected to aging cycles at 50 C. The results provide a new indicator to assess the fading of the state of health (SOH) of lithium titanate batteries during ultra-high-rate discharge cycles.

Air-core pulsed alternator (APA) is an ideal carrier for a high-power pulsed power supply because of the advantages of high-energy storage density and the discharge current crosses zero naturally. The upper limit of the magnetic field intensity and the adjustability of the electric excitation are higher and better than that of the permanent magnetic excitation, which bring the APA capable of discharging more flexibly. However, there is a problem for the engineering application of the APA of electric excitation. When the voltage is changing abruptly, there is a high-frequency voltage oscillation (HFVO) at both ends of the field coil. This problem is studied in this article, taking the separate excitation(a form of the electric excitation) as an example. First, the moment and reason of the HFVO are determined. Second, the equivalent circuit of the moment of the HFVO is modeled, and the analytical expression of the equivalent circuit and the stray capacitance value are derived. Third, the solution is proposed theoretically; that is, the resistance–capacitance (RC) series circuit is connected in parallel with the field coil or other equivalent positions. And, the derivation process of the parameters of the RC series circuit is given. The simulation and experimental results show that the parameters are appropriate. Finally, on the basis of the above, the extended research on self-excitation (another form of the electric excitation) is carried out.

Lithium titanate oxide (LTO) anode based lithium-ion battery has a large instantaneous output power and obvious uneven surface temperature distribution happens when discharging under ultrahigh discharge rates. To better know about the thermal characteristics, the thermal performance analysis of a 15 Ah LTO anode based pouch battery during the discharge is carried out under the discharge rates from 1C to 40C. In this work, the definition of different temperature zone is proposed, and four evaluation parameters are introduced to evaluate the temperature distribution from aspects of the temperature fluctuation, the aggregation degree, the time series similarity during the discharge process, and the distribution similarity under different discharge rates. Moreover, the strategy of the cooling device design is proposed. The results reveal the temperature distribution mode of the battery during the discharge. The similarity during each discharge rate is high. The battery has a fixed and aggregated high temperature zone at 10C and above, the medium temperature zone and low temperature zone moves outwards during the discharge, while the periphery of the battery is always in low temperature zone. Besides, the similarity between the adjacent discharge rates is high. In conclusion, this work reveals the temperature distribution mode of the battery and can instruct the specific cooling device design for the battery.

The fast charge and discharge performance of lithium-ion batteries (LIBs) is highly raised, which causes the temperature difference sharply increases. LIBs will be affected by improper thermal conditions, therefore, this work uses a novel iterative topology optimization method combined with finite element simulation to design a novel cooling plate for thermal homogeneity. The temperature difference of the battery is 14.4 °C under 40C discharge, and it decreases to 8.6 °C by using the cooling design. The temperature difference decreases up to 40%. The weight can be up to 80% lighter under the same temperature difference compared with the traditional cooling design. The novel method can be applied to different scenarios, which can decrease the temperature difference effectively and guide the structure design under complex heat sources with uneven heat generation.

锂离子电池的高功率密度和高能量密度等特性使其成为电动汽车能源和新能源电网储能的重要载体.功率性能和安全特性是锂离子电池发展的两个主要挑战.钛酸锂Li4Ti5O12材料因具有良好的结构稳定性、安全性能、长循环寿命、高功率特性和高低温放电性能,被认为是锂电池负极材料的良好备选.综述了以钛酸锂材料为负极的锂离子电池的相关工作,介绍了钛酸锂材料的结构、电化学特性、制备方法和作为电池负极材料面临的主要问题,重点介绍了钛酸锂负极电池的全电池性能和健康状态研究等方面.

电池组级联(BPCSs)电源的脉冲电容器电压是电磁推进的关键指标,重频模式下电池组多次为脉冲电容器充电后容量衰减,脉冲电容器电压在规定时间内达不到电压设定值,电磁推进的一致性将无法保证.基于BPCSs电源理论模型,提出一种时序动态调整算法,通过调整电池组串入回路的时刻来提高充电速度.实验结果表明:在电池组容量衰减40 V情况下,该算法充电时间缩短9.3％,平均电流提升10.2％,平均功率提升10.3％,能够保证重频模式下脉冲电容器电压及时达到设定值.

对锂离子电池的产热模型和散热技术进行综述,介绍目前锂离子电池领域风冷、液冷、相变冷却及复合冷却的发展情况.风冷效果的优化主要从冷却介质参数、结构参数及控制策略方面进行;液冷技术出现了散热能力强的微流体冷却,有望实现外部冷却到内部冷却的技术革新;相变冷却技术引入液气相变技术,实现了热量快速传递,可满足高倍率放电高散热量的需求;复合冷却技术将主动冷却与被动冷却结合,将传统冷却与新型冷却结合,可满足不同应用工况的需求.